Has anybody ever thought Dr.strange could've found the broken Mjölnir and kinda put it back together? That'd be a bit simple given that he has the time stone and that there was unusual energy when Hela appeared……. kinda makes you wonder.

The Infinity War trailer already shows Thor forging his new weapon using a massive machine to harness the energy of a dying star much which is a axe. Thor's hammer was also forged from a dying star. Peter Dinklage plays the elf that creates the the axe for Thor.